2. Infant massage: an infant sleep aid for reducing night wakings?

Although a variety of cultures practice infant massage, there has been little research on its effectiveness an an infant sleep aid.

However, the limited evidence suggests that massage could help.

In one study, researchers randomly assigned some mothers to introduce their babies (ranging from 3 to 18 months in age) to a massage-based bedtime routine. The intervention didn't make babies fall asleep any faster, but it seemed to help in other ways.

After two weeks, mothers reported that bedtime had become easier, and their babies experienced fewer night wakings. Mothers in a control group experienced no such improvements (Mindell et al 2018).

In another study, babies who received 14 days of massage therapy (beginning in the second week of life) seemed to adapt more quickly to the natural rhythms of day and night (Ferber 2002).

3. Skin-to-skin contact as an infant sleep aid

In modern-day hunter-gatherer societies, babies are often carried in slings against their mothers' naked skin. They also sleep with their mothers at night (Konner 2007).

As a result, these babies get lots of skin-to-skin contact. Does this contact function as an infant sleep aid?

Scientific studies of Western infants show that skin-to-skin contact, also known as "kangaroo care," has a painkilling effect on babies (Gray et al 2000).

It is also likely to boost an infant's levels of oxytocin, a hormone with sedative effects (Uvnas-Moberg 2003).

So it seems plausible that giving babies a little kangaroo care before bedtime might help them sleep better. But as of June 2018, I can find no randomized, controlled studies testing this idea. Researchers have begun one such study (Cooijmans et al 2017); we may learn the outcome soon.

4. Swaddling can be a helpful infant sleep aid -- but be sure to follow safety guidelines

Swaddled babies are wrapped in
cloths or blankets that restrict movement. As a result, they can't move less forcefully during the frequent startles that accompany infant sleep. Does that help babies stay asleep?
Research supports the idea.

In three different experiments,
infants who were swaddled and place on their backs showed improvements in
sleep. They experienced fewer startles, awoke less often, and spent more time
sleeping (Gerard et al 2002; Franco et al 2005; Meyer and Erler 2001).

So swaddling can be an effective
infant sleep aid. But it can also be dangerous, so it's crucial to follow safety guidelines.

It's important to avoid swaddling a
baby's chest so tightly that he or she can't inhale deeply. Tight swaddling has been
linked with higher rates of respiratory infections.

In addition, there is a potential
for overheating, particularly if the baby's head is covered, or if the baby has
a fever. And babies shouldn't be wrapped so tightly that they can't rotate their hips and flex their knees. Immobilizing babies in this way puts them at risk for hip displasia.

Finally, there is evidence that swaddling can increase the risk of SIDS, or sudden infant death syndrome. Studies show that SIDS victims are more likely to have been swaddled. The highest risk is associated with swaddled babies who are placed on their stomachs. Babies placed on their sides or backs seem to be at less risk, but the risk is still there, perhaps because some babies manage to move onto their stomachs (Pease et al 2016).

For this reason, experts recommend that you always place swaddled babies on their backs (the least risky position), and stop swaddling altogether once babies appear capable of turning themselves over (Pease et al 2016).

So overall, it seems to boil down to this:

don't wrap babies tightly

don't cover their heads, or otherwise let babies get overheated

don't constrict the hips or prevent babies from bending their knees, and

make sure that swaddled babies remains on their backs.

For tips on safe swaddling, watch this instructional video.

5. Daytime light exposure as an infant sleep aid

You might not think of a walk in the sunlight as an infant sleep aid. But it could help your baby better at night.

Why?

It's because of your baby's internal circadian rhythms -- physiological cycles that repeat over an approximately 24-hour period. When babies are born, these internal rhythms aren't synchronized with the rhythms of the external, 24-hour day (Rikvees 2003). As a result, babies can wake and sleep at odd times -- and wear us out.

But we can help babies get in sync by providing them with strong daytime cues -- exposing them to natural light during the day, and including them in our daytime activities. Both tactics are associated with faster synchronization (Thomas et al 2016; Harrison 2004; Wulff and Siegmund 2002).

6. Avoiding nighttime light -- especially the blue wavelengths.

Research confirms that light exposure at night sends a powerful, sleep-busting signal to the brain: Stay alert. Delay the release of the hormone, melatonin, that facilitates relaxation and drowsiness.

As I note in this article, young children may be especially sensitive to the sleep-busting effects of artificial lighting, and the blue wavelengths may have the most disruptive effects.

So in the evenings, shift to dim lighting. Try to protect your baby from light exposure in the middle of the night. And use light bulbs and blue-light filters that are designed to block the blue wavelengths that are especially likely to cause sleep disruption.

But it's crucial to keep the volume turned down, especially if the machine is placed close to the infant. You don't want to harm your baby's hearing.

When researchers investigated 14 different white noise machines being marketed for infants, they found that all of them could be turned up to dangerously high volumes -- volumes that would expose an infant 30 cm away to more than 50 decibels.

And three of the machines at this distance produced sound in excess of 80 decibels -- enough, when exposed for more than 8 hours a day, to put an adult at risk for hearing loss (Hugh et al 2014).

This might sound like a major spoiler. What's the point of using a white noise machine if you can't turn up the volume high enough blot out other sounds?

But I suspect that's the wrong premise. We don't need to blot out all background sounds in order to aid sleep. Instead, certain types of muffled, rhythmic sound may influence sleep by encouraging the brain to adopt or maintain the slower, rhythmic brain waves associated with sleep (Bellesi et al 2014; Papalambros et al 2017).

If this is the case, then soothing sounds played at a moderate, safe volume may help babies sleep -- even if other noises can be heard as well.

8. The pacifier: No compelling evidence that it helps babies sleep

Is the pacifier an effective sleep aid? The evidence is inconclusive at best.

Yes, there is reason to think that pacifiers soothe babies. When babies are subjected to painful medical procedures (like a heel prick to draw blood), sucking on a pacifier appears to reduce their perception of pain (Campos 1994; Blass and Watt 1999).

But there’s a catch: The
pain-reducing effect seems to work only as long as the infant is
actually sucking on the pacifier (Campos 1994).

That could be a problem when it comes to using a pacifier as a sleep aid. When the
pacifier falls out of the baby’s mouth, the soothing effect ends. And
the pacifier will fall out of the baby’s mouth.

In a study that recorded
the sleep patterns of babies aged 6-18 weeks, almost two-thirds of
infants lost their pacifiers within 30 minutes of falling asleep (Franco
et al 2004).

Perhaps that's why researchers have failed to turn up evidence that pacifiers make a difference for infant sleep. In one survey, researchers found that babies who sucked on their own thumbs or fingers slept longer at night, and experienced few night wakings.

By contrast, babies who used pacifiers showed no such such advantages. Their outcomes were similar to those of babies who didn't suck on anything at all (Butler et al 2016).

Are there any other benefits to sucking on a pacifier at night? It's possible that pacifier use might reduce an infant's risk for sudden infant death syndrome, or SIDS. One study reports that infants who use
pacifiers arouse more easily to disruptive sounds -- and the tendency to arouse quickly is generally protective against SIDS (Franco et al 2000).

But we're currently lacking the sort of rigorous studies that might confirm this effect. When researchers reviewed the published research, they could find no randomized, controlled studies testing the effectiveness of pacifiers for the reduction of SIDS risk (Butler et al 2016).

9. Rocking babies to sleep: Weighing the costs and benefits

Is rocking an effective infant sleep aid? It might work well for some babies. But parents should consider two potential problems.

The first is that rocking a baby in your arms might actually be too stimulating (France and Blampied 1999).

For instance, in a study that monitored newborns during a painful medical procedure (the heel prick described above), babies were either (1) held and rocked, or (2) given a pacifier to suck.

Compared with the babies given a pacifier, the infants who were rocked showed reduced rates of crying. But they were more likely to remain awake and alert (Campos 1994).

The other potential problem concerns rocking babies to sleep in cradles. Cradle-rocking is a widely practiced infant sleep aid, and many parents report that it helps babies fall asleep. But some sleep researchers are concerned that babies will come to associate falling asleep with being rocked in the cradle.

As a result, when these babies experience arousals during the night (as all babies do) they won’t be able to go back to sleep without being rocked again. So they wake all the way up and cry for help.

Although this sounds very plausible, I haven't found experimental support for this claim. However, a survey of Thai infant sleep patterns has reported that infants who sleep in swinging or rocking cradles are more likely to experience frequent night wakings (Anuntaseree et al 2007).

10. Lavender as an infant sleep aid: Does it work?

You might have seen claims that lavender oil is an effective infant sleep aid. What does the evidence really say?

A number of studies have shown that people exposed to the scent of lavender feel more relaxed and spend a greater percentage of time in deep sleep (e.g., Goel et al 2005).

There is also a study reporting that mothers who bathed their young infants in water scented with lavender-scented bath oil experienced benefits (Field et al 2007).

The mothers became more relaxed, touched their infants more often, and smiled at their infants more often. The infants, in turn, looked at their mothers more. They cried less often, and spent more time in deep sleep after the bath. Both mothers and infants showed reduced levels of cortisol (the stress hormone) after bath-time.

These results make lavender sound like a helpful infant sleep aid, but it's not clear that the lavender was directly responsible for the soothing effects.

A study published in the British Journal of Health Psychology tested the possibility that lavender aromatherapy works because people like the smell and expect it to relax them (Hughes and Hughes 2008). Before exposing people to the scent of lavender, researchers either told them that lavender was relaxing or stimulating. The results showed that people became more or less relaxed as a function of what they were led to expect.

So if lavender is an effective infant sleep aid, it might be because the fragrance makes parents feel more relaxed -- and more likely to behave in ways that keep babies calm.

Should you use lavender-scented products? If you find the scent soothing, it might be a good idea.

But there is reason to be cautious about applying lavender oil directly to your baby’s skin. Lavender oil contains estrogen-mimicking compounds, and there is some clinical evidence (based on three case studies) suggesting that the topical application of lavender oil may cause breast growth in preadolescents (Henley et al 2007).

11. Toys and other comfort objects: Do they promote better sleep?

Pillows, stuffed toys, blankets, and other soft objects can pose an asphyxiation hazard to babies under 12 months of age. So safety experts urge that we keep such objects out of a young infant's crib or cot.

But suppose you had a toy or other "comfort object" that didn't pose a risk. Are such items effective infant sleep aids?

It might seem like a no-brainer if you grew up in certain Western countries. Giving comfort objects to sleep with is a common folk practice -- one designed to help children fall asleep on their own.

But when researchers investigated the phenomenon in babies, they didn't find any evidence that comfort objects have any discernible effect on an infant's ability to fall asleep independently.

The study tracked
infants in four age groups (3, 6, 9 and 12-month olds) over a period of 3
months (Burnham et al 2002).

Infants were videotaped in their own homes
while they slept, and scored as "self-soothing" if, after awakening during the night, they managed to fall back to sleep without parental intervention.

Researchers also noted where babies slept, and whether or not the babies touched, held or sucked on any objects during the night -- objects that included pacifiers, toys, blankets, and the babies' own hands.

How did things turn out? Babies were more likely to use "comfort objects" if they were put to bed while still awake. And, overall, about 90% of babies used some sort of infant sleep aid, at least occasionally.

But there was no significant correlation between self-soothing and using a comfort object.

Why not? Previous research reported that comfort objects were helpful for a somewhat older group of infants (8 months and up). So it's possible that this is something that emerges naturally in some infants as they get older (Anders
et al 1992; Burnham et al 2002). Meanwhile, it seems that that safety concerns and sleep research point in the same diretion

12. Dream feeding: Does it help babies sleep longer?

Dream feeding is the practice of "tanking up" your baby immediately before you try to fall asleep.

It's typically done while the baby is already asleep, so it isn't intended as a method to help babies fall asleep.

But it may help ensure that you get a bit more time to sleep before your baby awakens. And in this respect, dream feeding could be a useful infant sleep aid for encouraging longer sleep bouts. Read more about it here.

13. Nursing a baby to sleep: The ultimate sleep aid?

Throughout human history, whether breastfed or bottle-bed, babies have been nursed to sleep. It is probably the most reliable infant sleep aid in existence.

Why is it so effective? To some degree, it's
obvious. Hunger is an unpleasant sensation. Sate the hunger, and a baby is going to feel more comfortable and
relaxed afterwards.

But there is more to it than that.

First, it isn't just a question of calories. Newborns cry less and
seem to experience less pain when they receive very small amounts of milk,
formula, or sucrose (see review by Shaw et al 2007; also Blass 1997a;
Blass 1997b; Blass and Watt 1999; Barr et al 1999). Moreover, the act of
sucking--even sucking a pacifier--has a calming effect (Blass and Watt
1999).

Second, infants who breastfeed experience skin-to-skin contact, which may be an effective infant sleep aid in its own right (see infant sleep aid #3).

In addition, breastfeeding boosts a mother's oxytocin levels, which can enhance her maternal feelings and impart a sense of calm (Keverne
1996). Such psychological changes may make it easier for her to soothe her infant.

So feeding can be a powerful infant sleep aid. Yet it is controversial. Why?

One reason concerns the question of timing.

Parents who use feeding as an infant sleep aid may tend to feed their infants more often, and some researchers believe high-frequency feedings could interfere with the development of longer sleep bouts at night.

For example, one study found that newborns who were fed frequently during the first
week postpartum—more than 11 times during each 24 hour period—were 2.7
times more likely than were other infants to have problems at 12 weeks (Nikolopoulou and St James-Roberts 2003).

But research like this can't tell us if frequent feedings cause sleep problems. It may be that some infants are needier than
others, and that those who need to feed frequently during the first week
postpartum continue to need frequent night feedings later on.

The other source of controversy concerns self-soothing.

Although feeding may be an effective infant sleep aid in the short-term, it might discourage babies from developing the ability to fall asleep on their own.

Western sleep researchers often advise against
letting babies fall asleep in their parents' arms. Instead, they
recommend that babies be put to bed while still awake. If babies cry,
parents should resist the temptation to soothe them—at least for a few
minutes. By holding back, parents will force babies to acquire their own "self-soothing" skills, and babies will learn to fall asleep by
themselves. When babies experience arousals during the night, they will
soothe themselves back to sleep without awakening their parents (France
and Blampied 1999; Ferber 2006).

There is strong evidence to
support these claims. Babies who are put to bed before they fall asleep
are indeed more likely to soothe themselves back to sleep when they
awaken again during the night (e.g., Anders 1979; Anders et al 1992;
Ferber 1986; Goodlin-Jones et al 2001).

But does this mean you
shouldn't allow your baby to fall asleep during a feeding? Maybe not.

Feeding appears to be a natural infant sleep aid, and soothing babies to
sleep is the norm for our species. In many parts of the world, babies
routinely fall asleep at the breast, and their parents don't perceive
this to be a problem.

Moreover, some researchers are concerned about the physiological and
psychological effects of strictly-imposed, solitary sleep regimens. Typically,
babies don't adjust to such regimens without experiencing transitional
distress. And even
those who advocate sleep training for babies warn that "cry it out" methods are inappropriate for babies less than 6 months (France and
Blampied 1996; Owens et al 1999).

For more information, see this article about the most famous regimen associated with "cry it out" methods -- the Ferber method.

Additional reading: Dream feeding as an infant sleep aid

"Dream feeding" refers to the practice of timing a large meal so that it occurs immediately before the parent tries to go to sleep. According to Tracey Hogg, who coined the term, dream feeding also means feeding an infant while he or she sleeps.

There is reason to think the practice may give parents a little more time to sleep, and for exhausted parents, even a little more sleep time could yield important health benefits. Read more about dream feeding here.

References: Finding the right infant sleep aid

American Academy of Pediatrics. 1997. Breastfeeding and the Use of Human Milk. Pediatrics 100 (6): 1035-1039.

Anders TF. 1979. Night waking in infants during the first year of life. Pediatrics 63: 860-864.